You might try the attached script. After you guys test it, let me know how it works. Once it is finished, I will release it on the Custom Addons forum. Make sure that when you install it, you es_load gungame51, then change the setting in the newly created ../cfg/gungame51/custom_addon_configs/gg_knifepro_noswitch.cfg file to 1, and finally reload gungame51 or restart the server.
*Edit: I had some time to test it, and got it working properly:
viewtopic.php?f=74&t=2112Satoon